Thin-walled tube cold-rolling mill

ABSTRACT

A mill with travelling stand, wherein to eliminate sliding of the passes on a tube being rolled, there is a mechanism for moving the racks during mill operation, the mechanism being designed so as to ensure variations in the rolling radius when the tube is strained.

Orro et a1.

[ THIN-WALLED TUBE COLD-ROLLING MILL [76] Inventors: Pavel lvanovich Orro, ulitsa Kirova,

8, kv. 25, Dnepropetrovsk, U.S.S.R'.; Anatoly Vasilievich Kirilenlro, deceased, late of ulitsa Kirova, 7/4, late of Dnepropetrovsk, U.S.S.R. by Nilla Sergeevna Kirilenko, administratrix 22 Filed: July 7, 1972 [21-] Appl. No.: 269,817

52 u.s.c|. ..72/208,72/214 51 mo: ..B21b 17/10 58 FieldofSearch 72/189, 208, 209,214

[4 1 May 14,1974

[56] I References Cited UNITED STATES PATENTS 2,161,065 6/1939 Krause 72/209 3,570,294 3/1971 Shibota.... 72/189 X 3,030,835 4/1962 Krause 72/214 X Primary Examiner-Milton S. Mehr Attorney, Agent, or Firm-Holman & Stern [57] ABSTRACT A mill with travelling stand, wherein to eliminate sliding of the passes on a tube being rolled, there is a mechanism for moving the racks during mill operation, the 'mechanism being designed so as to ensure variations in the rolling radius when the tube is strained.

3 Claims, 6 Drawing Figures 1 THIN-WALLEI) TUBE COLD-ROLLING MILL BACKGROUND OF THE INVENTION The present invention relates generally to the production of tubes and more particularly, it relates to mills for cold rolling of thin-walled tubes.

A mill for cold rolling of thinand superthin-walled tubes is known in the art, comprising a working stand with reeling and straining rolls with variable section passes housed therein on supports, end gears fit on the rolls toensure reciprocating motion of the stand and the rolls, gear racks for end gears to run thereon and locate the position of the rolls, and a motor with a drive to ensure the operation of the whole mill, as well as a tube-feeding and swinging mechanism (cf. US. Pat. No. 3.030.835 of Apr. 24, 1962).

In the known tube cold-rolling mill they use drive gears on the rolls that ensure an average running radius throughout the entire length of the roll pass.

This affects rolling due to excessive sliding of the pass along the tube and leads to an increased number of cases when a tube to be rolled and a pushing tube run, with ends, into each other and when the ends of the tubes crack too much at the start of rolling.

SUMMARY OF THE INVENTION The object of the present invention is to provide a mill for cold rolling of thin-walled tubes so as to help reduce sliding of the pass alongthe tube, eliminate run ning of the ends of a tube to be rolled and a pushing tube into each other and cracking of the tubes ends at the start of rolling.

This and other objects of the invention have been achieved by providing a thin-walled tube cold-rolling mill. I I

' It is an object of the present invention to eliminate the above-mentioned disadvantages.

There is proposed a mill for cold rolling of thinwalled tubes, comprising a working stand with reeling and straining rolls with variable section passes housed therein on supports, end gears fitted on the rolls to ensure reciprocating motion of the stand and the rolls,

gear racks for the end gears to run thereon and to locate the position'of the rolls, and a motor with a drive to ensure the operation of the whole mill, as well as a mechanism for feeding and swinging a tube 'to be rolled. According to the invention, the gear racks are set with the possibility of their longitudinal travel in directions of the travel of the stand whenever a critical frictional force develops in rolling between the pass and a tube being rolled as the rolling radius of the pass is varied; coupled with the racks is a mechanism designed to return said racks to their original position as soon as they are relieved from load caused by the frictional force. i

It is expedient that the mechanism for returning the racks to their original position be made as a shockabsorbing device fitted with springs and coupled with the racks.

While straining tubes, this will help the gear racks to travel under the action of natural frictional forces according to the law of a variable running radius and to compress one of the springs of the shock-absorbing device, and once straining is over, the racks are free to return to their original position, which helps reduce to 2 the minimum the sliding friction of the pass against a tube in rolling. i

It is also feasible to fashion the mechanism for returning the gear racks to their original position as a cam coupled with the gear racks, which also helps reduce to the minimum the sliding friction of the pass against the tube in rolling.

The embodiment of the present invention is a mill for cold rolling of thinand superthin-walled tubes, which offers the following advantages: it helps increase the efficiency of the mill two-or three-fold, reduce the number of intermediate preparatory operations 25 to 35 percent, and increase the rolling-down ofa tube up to 50 percent in diameter and up to percent through the thickness of the wall.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 3 and 4 show the mechanism for moving the racks with provision of a spring shock-absorber;

FIGS. 5 and 6 show the mechanism for moving the racks with provision of a cam.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the mill for cold rolling of thinand superthin-walled tubes has a rectangular working stand 1 resting on rolls 2 that enable its unopposed movement in forward and reverse directions. In the upper and lower sections of the stand I, there are tempered steel base plates 3 over which rolls 4 are rollmg.

The stand I is the basic operating mechanism of the mill, wherein the tube is strained by means of rolling tools, i.e., the rolls 4 and an arbor 5.

.A round pass 6 of variable section is shaped and grounded on the rolls 4. When unrolled, it has a tapered shape which helps strain the tube in diameter and through the thickness of the wall in rolling.

Provided for adjusting and controlling the rolls 4 in the upper and lower portions of the stand 1 are wedges 7 with whose help the base plates 3 can draw together or break up.

Set on the two ends of the rolls 4 are cylindrical wheels 8 coupling both rolls 4 to each other and ensuring synchronism of their movement. In addition to the cylindrical wheels there are drive gears 9 set supplementarily on the lower roll 4 alone, specifically on both ends of it, the drive gears being meshed in its upper part with the gear racks l0 and, in its lower part, with mov ing gear racks 11 provided in the stand 1 of the mill.

By one of its ends, the gear racks 10 are secured on ma shock absorber l2 loaded with springs 13. The gear racks 11 are rigidly fixed on the stand 1 with the capability of reciprocating motion together with the stand 1 FIGS. 3 and 4 show the shock absorber l2 loaded with the draw springs 13. The arrows indicate the direction of the racks travel in forward and reverse movement of the stand.

In the rear (as rolling proceeds) portion of the stand, there is a mechanism 14 designedto turn and feed a tube to be rolled, the mechanism enabling, the feed and the turn of the tube in a rear position alone or separately in each double stroke of the stand I. The turn and feed mechanism is of standard design similar to that used in serial cold-rolling mills.

The rearmost end of the mill accomodates a rest 15 for a rod 16, the rest helping to adjust and control the tapered arbor in a source of the strain. The arbor 5 is secured to the forward end of the rod 16 thanks to screw thread.

Prior to rolling, a tube 17 is put on the rod 16 with the arbor 5 secured, to be fed thereafter to the source of strain by means of the feed and turn mechanism 14.

From the front side of the stand 1, there are two ears l8 linked to connecting rods 19, the opposite ends of 'the connecting rods 19 being connected with crank pins 20 tightly pressed into the disks of crank gears 21.

Alternatively, a cam mechanism 26 shown in FIGS.

5 and 6 may be provided to replace the spring-loaded shock-absorber 13 to move the rack 10. In this case, the movement of the racks is carried out coercively by an eccentric disk 27 via rollers 28 to correspond to the movement of the passes 6 of the rolls 4 along the natural (variable) rolling radius. The directions of rotation of the disk 27 and the rollers 28 as well as of the travel of the racks are indicated by arrows.

The operation .of the above-described mill is as follows:

Prior to the mill operation, the rolling tools, i.e., rolls 4 and armor 5, calibrated as prescribed, are mounted into the stand 1 and then adjusted roughly. Furtheron, the tube 17 is put on the rod 16 with the arbor 5 to be conventionally secured within the feed and turn mechanism 14. The motor 24 is cut in to start a low-speed rolling. Via .the elastic wedge belts 22, the motor starts rotating the cranks gear wheels 21 as well as the crank pins 20. Coupled with the pins, the connecting rods 19 actuate the stand l in forward and reverse directions. The motion of the stand 1 results in moving the rolls 4 which turn by about 360, the diameter of the pass 6 getting smaller in forward movement, to count as from the direction of the tube movement, to comply with a prescribed calibration and ranging from the maximum to the minimum one which should correspond to the size of the ready tube 17; ln the course of movement of the stand 1, the rolls 4 move coercively along the base plates 3 due to meshing of a drive gear 9 with the gear racks l0 and 11.

During the idle operation of the mill, the gear rack 10 remains where it was and the movement of the rolls 4 takes place without axial effort. Therefore, the springa fitted shock-absorber 12 is not loaded. But as the rolling of the tube 17 starts, natural axial frictional forces develop between the tube 17 and the pass 6 on its surface within the source of strain because of the different rolling radii along the operating pass 6. These axial frictional forces are the more so powerful, the greater the difference between the running radii of the pass 6, Le,

the greater the taper of the tube under rolling within the strain source.

The axial frictional forces are subject to elimination as they cause considerable troubles in the mill operation: speedy wear of the passes, higher load on the racks 10 and 11, cracking of the ends of the tube 17, and running of the ends of a tube under rolling and a pushing tube into each other Elimination of the frictional forces is achieved by means of a spring-loaded shock-absorber 13 shown on FIGS. 3 and 4. The operation of the shock-absorber is that, under the action of frictional forces,-the racks 10 move along the rolling axis and compress the springs 13 in this or that direction depending upon forward or reverse travel of the stand. This helps eliminate variable frictional forces emerging between the pass 6 and the tube 17 throughout the pass length. Once the rolling is over, the pass releases the tube, the action of frictional forces discontinue and the springs 13 of the shock-absorber return the racks 10 to the original average position. The directions of movement of the racks 10 are indicated by ar-' rows in FIG. 3. 7

Alternatively, there may be a cam mechanism 26 provided instead of the spring-loaded shock-absorber l3 and shown on FIGS. 5 and 6. The mechanism consists ofa frame 29 coupled rigidly with the racks 10. A shaft 30 of the frame 29 carries the eccentric disk 27 and two driven rollers 28. As the eccentric disk .is rotated by a shaft 31 of the drive, the driven rollers 28 move the rack 10in forward and reverse directions synchronously with a variation of the rolling radius. The arrows show the directions of the movement of the racks l0 and of the rotation of the shaft 31.

Provision of the spring-loaded shock-absorber 12 or the cam mechanism 27 helps eliminate also the axial frictional forces developing due to the different rolling radii of the pass.

After every double stroke of the stand 1, the turn and feed mechanism 14 effects feeding and turning of a tube to a prescribed value to enable the rolling of new portions of the tube to its preset diameter and wall thickness. Feeding and turning the tube can be effected separately: turn in forward position and feed in reverse. The designation of'the turn and feed mechanism 14 is to ensure even turning and feeding of the tube within one double travel of the stand.

The rod 16 with the arbor 5 is fixed rigidly on the rear stop 15, whereon tube reduction occurs. In order to facilitate the tube coming down off the arbor, the latter is made tapered.

After rolling the forward end of the tube throughout a limited length, adjustment is checked and, if necessary, corrected. If not, the tube is subject to rolling throughout its length.

What we claim is: v

1. A thin-walled tube cold-rolling mill comprising: a moving working stand; reeling and straining rolls with passes of variable section being provided in said stand; gear racks being set in said stand and travelling together with said stand during the mill operation; gear racks being mounted on said mill and capable of longitudinal travelling in direction of the movement of said stand whenever a critical frictional force develops in rolling between said pass and a tube to be rolled as the rolling radius of said pass is varied; end gears being fitted on said rolls to couple the latter to each other and to ensure synchronism of their movement, drive end gears being fitted on one of said rolls and meshed with said stand-mounted gear racks and with said gear racks provided on said mill, said drive end gears rolling on them and locating the position of said roll; means for feeding and turning the tube to be rolled being provided in the rear section of said mill to ensure even turning and feeding of the tube in one double stroke of said stand; dampening means for returning said gear racks mounted on said mill to their initial position after relieving them from the load caused by the frictional force; and a motor having a reducing gear, said reducing gear being designed to ensure the operation of all the mechanism of said mill.

2. A mill as'claimed in claim 1, wherein said dampening means for returning said gear racks mounted on said mill to their initial position is made as a springloadedshock-absorber coupled with said gear racks.

3. A mill as claimed in claim I, wherein said dampen ing means for returning said gear racks mounted on the mill to their initial position is made as a cam mechanism comprising a frame fixed rigidly with said gear racks mounted on said mill and coupled with a drive shaft, said frame of said cam mechanism actuating said gear racks in directions of the movement of said stand synchronous with variations in the rolling radius of said pass. 

1. A thin-walled tube cold-rolling mill comprising: a moving working stand; reeling and straining rolls with passes of variable section being provided in said stand; gear racks being set in said stand and travelling together with said stand during the mill operation; gear racks being mounted on said mill and capable of longitudinal travelling in direction of the movement of said stand whenever a critical frictional force develops in rolling between said pass and a tube to be rolled as the rolling radius of said pass is varied; end gears being fitted on said rolls to couple the latter to each other and to ensure synchronism of their movement, drive end gears being fitted on one of said rolls and meshed with said stand-mounted gear racks and with said gear racks provided on said mill, said drive end gears rolling on them and locating the position of said roll; means for feeding and turning the tube to be rolled being provided in the rear section of said mill to ensure even turning and feeding of the tube in one double stroke of said stand; dampening means for returning said gear racks mounted on said mill to their initial position after relieving them from the load caused by the frictional force; and a motor having a reducing gear, said reducing gear being designed to ensure the operation of all the mechanism of said mill.
 2. A mill as claimed in claim 1, wherein said dampening means for returning said gear racks mounted on said mill to their initial position is made as a spring-loaded shock-absorber coupled with said gear racks.
 3. A mill as claimed in claim 1, wherein said dampening means for returning said gear racks mounted on the mill to their initial position is made as a cam mechanism comprising a frame fixed rigidly with said gear racks mounted on said mill and coupled with a drive shaft, said frame of said cam mechanism actuating said gear racks in directions of the movement of said stand synchronous with variations in the rolling radius of said pass. 